The present invention relates to a chair, in particular an office chair comprising a seat top with at least one front seat support arm and at least one rear seat support arm projecting at the underside of the seat top, a seat carrier which is securely connected to a central chair column or several chair legs, and a backrest which is arranged at a backrest carrier firstly extending under the seat top backwards and thereafter upwards with the backrest carrier supported by means of a crosswise horizontally extending backrest carrier swivelling joint with the front seat support arm articulately connected to the seat carrier through at least one lever wherein the rear seat support arm offset backwards from the backrest carrier swivelling joint is articulately connected to the backrest carrier by means of a crosswise horizontally extending rear seat joint, and wherein a spring arrangement is provided under the seat top with the spring arrangement exerting a biasing force upwards upon the seat top and forwardly upon the backrest.
A chair of the type mentioned is known from DE 43 13 301 C2. The spring arrangement provided for this chair consists of a pressure spring which is arranged between the seat carrier and the seat top. By the arrangement of the single parts of this chair as explained above the chair offers the user the opportunities to selectively sit upwards on this chair or in a reclined position. In the reclined position the seat top will lower in the rear part, whereby at the same time the backrest with the backrest carrier will pivot backwards.
It is a disadvantage of this known chair that it offers no possibility to adapt the force acting upon the back of the user to the user, in particular to the body weight thereof. Therefore the known chair is only a compromise regarding the force acted upon the back of the user by the backrest, which in many cases is not optimal, in particular when the chair is used by light weight or heavy weight users.